Machines such as, for example, off-highway haul trucks, motor graders, snow plows, and other types of heavy equipment are used to perform a variety of tasks. Some of these tasks involve carrying or pushing large, awkward, loose, and/or heavy loads up steep inclines or along rough or poorly marked haul roads. And, because of the size and momentum of the machines and/or because of poor visibility, these tasks can be difficult for a human operator to complete effectively.
To help guide the machines safely and efficiently along the haul roads, some machines are equipped with sensors, for example, RADAR sensors, SONAR sensors, LIDAR sensors, IR and non-IR cameras, and other similar sensors. These sensors are often connected to a visual display and/or a guidance system of the machine such that control over machine maneuvering may be enhanced or even automated. In order for these display and guidance systems to operate properly, the information provided by the sensors must be accurate. And, even though most machine sensor systems are calibrated when first commissioned, vibrations, collisions, and damage to the machine during operation can reduce the quality of information provided by the sensors. As such, periodic recalibration can be beneficial.
An exemplary recalibration system and method is described in U.S. Patent Publication No. 2006/0164295 (the '295 publication) by Focke et al. published on Jul. 27, 2006. Specifically, the '295 publication describes a system for simultaneous calibration of two different types of sensors, for example an image sensor and a radar sensor mounted on a motor vehicle. During calibration of the two sensors, the motor vehicle is aligned in front of a calibration object in such a way that the image and radar sensors detect reference features of the calibration object and responsively create calibration data. The calibration data used directly for calibration of the participating sensors. For example, the calibration data is used for automatic correction of a deviation of a sensor axis in relation to a vehicle longitudinal axis or by an automotive technician for mechanical adjustment of sensor placement. These procedures are possible during manufacture or repair of the motor vehicle.
Although the sensor system of the '295 publication may be helpful in recalibrating machine-mounted sensors, the benefit may be limited. That is, for optimum accuracy, the machine of the '295 publication must be precisely aligned relative to the calibration object. Any error in this alignment may result in an accuracy reduction of the sensed information. In addition, the mechanical adjustment of the sensor location on the motor vehicle may be time consuming and expensive, while the automated calibration described in the '295 patent (i.e., about only the sensor axis) may be limited.
The disclosed sensor calibration system is directed to overcoming one or more of the problems set forth above and/or other problems of the prior art.